Everytime I turn on my defrost weather I have the switch to cold or hot, my ac comes on, light comes on and I can feel it kick in... This cannot be normal can it? I have owned 5 different cars and driven many other and never had one where the ac always comes on with the defrost, I push the ac button and it wont turn off, but it turns off as soon as I switch it to vents or something else, I just want to be able to run my defrost without the ac robbing power, any ideas?

sorry, car is an 03 sunfire ecotec 5 speed...

It is designed to.....so whats the problem.
I'm not sure what other five cars you have driven, but most turn the AC on when the defrost is turned on.



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It's meant to do that--it actually works better that way because the a/c will pull moisture out of the air, and thus the drier air will pull the moisture off our windsheild and side windows.

If you want to not have it run like that, run the floor/defroster seting.


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Sucks for gas mileage/power though. I took my car in because I was having trouble with the hvac controls, and when I picked it up it never did it again. I noticed there is now a wire unplugged from the back of the unit, im not sure if thats what disabled it but you could give it a shot.

^ And by never did it again, I meant never turned on the ac when I put on the defroster.

When it gets colder outside, the AC compressor will not come on even when the light is ON. The threshold seems to be around -8C to -5C.
On a Ford Focus, the AC turns on too with the defrost setting but on that car you can manually turn it off by pressing the AC button

All the cars ive been in have this. put it on the vent/floor if you don't want it on.

My wifes 2003 gagt doesn't even do this which is one of the cars I mentioned, at lest the ac light doesn't come on when its on defrost, ford probe, 89 cavalier z24 convertable didn't as far as i remember nor any of the fieros I have driven, maybe it becasue they were all older cars... hmm, I still don't like it, I can really feel the difference in power with it on especially since I installed my light weight pulleys, I seems much more drastic every time the ac kicks in

02 cavy... does the same thing... i just use the floor/defrost... works just as good.. and your feet get warm at the same time!! lol

Actually, when my g/f had a 03 sunfire, when she used either the defrost/floor or defrost setting the AC would turn on.


Ryan1

just pull the fuse/relay for the compressor that's what i do when it gets cold enough to save on some gas money


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floor setting does it too so does the one all the way to the left whatever it is, only ones that dont are vents, vents/floor and floor only

i got an 04 cav 5 speed and it does this too...if the symbol is orange it will turn the ac on....i just put it on the window vent/floor like every one else....its completely normal....

air conditioner= conditions the air. if its on its conditioning the air so it doesnt fog up. its normal.

This is normal. Why would you have the AC on when trying to get the most performance?? The A/C is programed to cut off at certain RPMS for performance, so it really is not hurting performance.



FU Tuning

Will Paulman wrote:floor setting does it too so does the one all the way to the left whatever it is, only ones that dont are vents, vents/floor and floor only

Must be a 2003 thing.... my 01 sunfire gt only has the a/c on when full defrost is selected same with my sisters 01 cav ls sport and my parents 04 sunfire sedan....